J Chromatogr. A, 1652, 462377 (2021). Samples were vanilla tinctures, water − ethanol − ethyl acetate 1:1:1 extracts of vanilla-flavored food products and of natural Vanilla sp. (Orchidaceae) pods, oleoresin, paste and powders, as well as calibration standards of vanillin (1) and ethylvanillin (2). HPTLC on silica gel with n-hexane – ethyl acetate 1:1 for profiling, 3:2 for quantification. Other mobile phases were also tested and given in the supplement. Compounds (1) and (2) (hRF 68 and 82, respectively) were quantified by absorbance densitometry (at maximal wavelength 310 nm, deuterium lamp, scanning speed 10mm/s). Contents were found to be between 1 μg/g and 36 mg/g for (1) and null for (2) except in one tincture (62 µg/mL). Derivatizations performed for five assays: A) to detect radical scavengers, immersion (speed 3 cm/s, time 5 s) into DPPH• (0.5 mM in methanol), followed by drying for 90 s at room temperature and 30 s at 60 °C; B) to detect activity against Gram-negative bacteria, immersion (speed 2 cm/s, time 3 s) into Aliivibrio fischeri suspension, followed by recording the bioluminescence; C) to detect activity against Gram-positive bacteria, immersion (speed 3.5 cm/s, time 6 s) into Bacillus subtilis, followed by incubation 2 h at 37 °C, immersion in MTT solution, incubation for 30 min at 37 °C and heating for 5 min at 50 °C; D) to detect acetylcholinesterase (AChE) inhibitors, immersion (speed 2.5 cm/s, time 2 s) into AChE solution (666 units in TRIS buffer 0.05M, with bovine serum albumin 0.1 %, pH 7.8), incubation for 25 min at 37 °C and immersion into substrate solution (α-naphthyl acetate 0.1 % and Fast Blue salt B 0.18 % in ethanol – water, 1:2; E) to detect tyrosinase inhibitors, spraying with enzyme solution (400 unit/mL, in phosphate buffer 0.02 M, pH 6.8), followed by 2 min drying, immersion into substrate levodopa (18 mM in phosphate buffer, pH 6.8), 10 min incubation at room temperature and drying. For identification, zones of interest were transferred with methanol from underivatized HPTLC layer through a TLC-MS interface and a filter frit directly to a Quadrupole-Orbitrap MS (heated electrospray ionization, probe heater at 270°C, spray voltage 3.5kV, lock masses acetic acid for negative, dibutyl phthalate for positive ionization, mode full HR-MS scan in m/z range 50–750). Afterwards, the following substances assigned by MS were confirmed by using HPTLC comparison with standards: (1) and (2), vanillyl alcohol, vanillic acid, ethyl vanillyl ether, coumarin, 4-hydroxybenzoic acid, 4-methoxybenzoic acid, 4-hydroxybenzaldehyde, 4-allyl benzoic acid, oleamide, triacetin.

Chromatography Research International 2014, 626801 (2014). HPTLC of extracts of Gymnema sylvestre (Apocynaceae) in tablets, as well as standards for calibration, on silica gel (prewashed with methanol and activated at 120°C for 15 min) with toluene – ethyl acetate – methanol 65:25:14. Derivatization by immersing into sulfuric acid (5 % in methanol) and heating at 110°C for 4 min. Densitometric evaluation within 25 min in absorbance mode at 423 nm, which was the optimal wavelength for quantifying simultaneously the triterpenoid gymnemagenin (hRF 27, linearity range 100–1200 ng/band, LOD 32 ng/band, LOQ 53 ng/band) and β-sitosterol (hRF 78, linearity range 200–1200 ng/band, LOD 97 ng/band, LOQ 159 ng/band). Interday and intra-day precisions as well as recovery rates provided relative deviation values below 1 %. This method was used to determine the analyte contents in the tablets (0.041 % gymnemagenin and 0.138 % β-sitosterol), as well as to confirm the stability of the analytes in solution at room temperature after 48h.   

Frontiers in Marine Science 7, 266 (2020). Methanol extracts from marine sponge Haliclona cnidata (Chalinidae) submitted to different stresses (antibiotics and/or darkness) were separated on HPTLC silica gel with an automated 15-step gradient based on methanol, dichloromethane and n-hexane. Bioluminescence was recorded after immersing the HPTLC plates into Aliivibrio fischeri suspension. Antibacterial activity and quorum sensing enhancement were analysed on software, and Pearson’s similarity coefficient was applied to generate similarity matrices for cluster analysis (UPGMA, Unweighted Pair Group Method with Arithmetic Mean). Only slight differences were observed, especially in QS enhanced zones in stressed vs. control cultures.

Nature - Lab. Invest. 100, 1411–1424 (2020). Samples were chloroform – methanol 1:1 solutions of lipid standards and of liver tissue extracts from wild-type mice (1), from transgenic murine models of hepatic steatosis (2) (mice expressing HBs, hepatitis B virus surface protein), or of cholestasis (3) (mice totally knock-out for the gene of phospholipid translocator ABCB4, ATP-binding cassette subfamily B member 4), or of both (4) (hybrids of mice (2) and (3)). HPTLC on silica gel (preheated at 110°C for 15 min) with n-hexane – diethyl ether – acetic acid 20:5:1. (A) For qualitative analysis, visualization under white light after immersion into anisaldehyde 0.5 % (in sulfuric acid – acetic acid – methanol, 1:2:17), followed by heating at 110°C for 9 min. (B) Identification of lipids was confirmed by elution of the zones of interest with methanol from the HPTLC layer through a TLC-MS interface and a filter frit directly to a quadrupole-orbitrap MS (atmospheric pressure chemical ionization, full HR-MS scan in m/z range 100–1000). (C) For quantitative analysis, visualization at UV 366 nm after derivatization by immersion into primuline reagent (primuline 0.5 g/L in acetone – water 4:1); fluorescence was measured at UV 366 nm (mercury lamp, optical filter for wavelengths above 400 nm, scanning slit 6.0 mm × 0.2 mm, speed 20 mm/s). (A) and (B) allowed the separation and detection of cholesterol, cholesteryl oleate, methyl oleate, free fatty acids (FFA, expressed as oleic acid equivalents) and triacylglycerols (TAG, as triolein equivalents) in liver extracts. (C) showed that TAG was decreased and FFA increased in (3) and (4), compared to (1) and (2). Cholesterol and cholesteryl oleate had no significant changes between groups.

J. Chromatogr. Sci., 59 (10), 964-970 (2021). Introduction of an accurate and sensitive method for the simultaneous determination of thioctic acid, benfotiamine and cyanocobalamin in bulk powders and in their pharmaceutical formulation. TLC on silica gel with methanol - chloroform - heptane-1 - o.4 % sulfonic acid sodium salt 70:30:1. Determination by densitometric evaluation at 240 nm. The hRf values were 17, 48 and 75 for cyanocobalamin, benfotiamine and thioctic acid, respectively.

Sci. World J. 2020, 7367836 (2020). TLC of ethyl acetate fractions of hydro ethanolic extracts obtained from Cassia siamea leaves (Caesalpiniaceae) on silica gel with chloroform – ethanol 17:3, as well as cassiarin A (an isoquinoline alkaloid, hRF 34) as standard. Visualization under UV light. Densitometry scanning at 368 nm for cassiarin A. Linearity was in the range of 400–1400 ng; intra-day precision was below 4 %; LOD and LOQ values were 3 and 8 ng, respectively; recovery rates were 102.8–120.1 %. The cassiarin A concentrations in the samples (given as w/v, the volumes being those of the first undried hydro-ethanolic extracts) varied depending on the origin (ground and climate) of the leaves.

Foods 9(8), 1136 (2020). TLC of methanolic decoctions and ultrasonication extracts from Zingiber officinale (Zingiberaceae) rhizomes, as well as from commercial ginger formulations, on reverse-phase C18-silica gel with ethanol – water 13:7. Densitometry at 200 nm in absorbance and reflectance modes for 6-shogaol (SHO, hRF 36) and 6-gingerol (GIN, hRF 53). Standards of these vanilloid phenolics were also used for calibration; linearity was in the range of 100–700 ng for SHO and of 50–600 ng/band for GIN; interday and intra-day precisions were below 1.6 %. The LOD and LOQ was 34 and 101 ng for SHO, 17 and 51 ng for GIN, respectively. Recovery rates were 98.8–101.6 % for SHO and 99.0–101.5 % for GIN. For each extract, SHO and GIN levels were calculated, the yields after ultrasonication extraction were 10-25 % higher than with the corresponding decoctions. Comparison with other published methods (LC-MS and HPLC) showed superiority of this new method in terms of linearity range, accuracy and precision.

3 Biotech 10(8), 344 (2020). Rauvolfia serpentina (Apocynaceae) was cultivated in vitro as leaf-derived callus and as plantlet cultures obtained from tissues of nodal explants, without or with cadmium chloride as elicitor of alkaloid production. TLC of methanol – ammonia 10:1 extracts of callus and plantlet organs (leaves, stems and roots) on silica gel, along with indole alkaloids reserpine and ajmalicine in different concentrations. Development with chloroform – toluene – ethyl acetate – diethyl amine 7:7:4:1. Detection under UV light and by densitometry scanning in absorbance mode at 240 nm and 280 nm. The highest alkaloid yields were obtained for reserpine (hRF 15) in roots (191µg/g) and for ajmalicine (hRF 45) in callus (131µg/ml) when culture had been done with elicitor 0.15 mM for 6 days and 4 days, respectively (at 0.20 mM, an inhibiting effect was observed).